The present invention, relates to a method for producing a catalyst that is involved in the reaction for the production of hydrocyanic acid and water by thermal decomposition of formamide. It more specifically relates to a catalyst production method which may be put into practice commercially using an extremely simple process which does not make use of corrosive liquid reagents or the like during the preparation of a catalyst and which does not require further treatment after preparation.
Methods for the synthesis of hydrocyanic acid by the selective thermal decomposition of formamide using a catalyst made from a metal or a metal oxide have long been known. With regard to the catalyst used, many are known in the prior art, and, for example, cyanide is synthesized from formamide using a pipe catalyst prepared by impregnating aluminum into the surface of a reaction pipe using a melted aluminum bath to create an iron-aluminum alloy as is reported in Japanese Patent 1960-9182. Additionally Japanese Patent 1958-6229 discloses a method for preparing catalyst by treating a saturated solution of potassium bichromate in concentrated sulfuric acid, a solution of potassium permanganate in concentrated sulfuric acid, aqueous hydrogen peroxide and the like. To carry out these methods on an industrial scale, it is necessary to prepare several specialized items of equipment for conducting various treatments.
The method according to Japanese Patent 1960-9182 for preparing an oxidized layer where a steel pipe is used in the reactor requires a very large investment for the application of industrial equipment made of multiple pipe reactors by methods for preparing reaction pipes. In addition where an oxidative reagent is used in the same manner as in Japanese Patent 1958-6229, it is necessary to add a separate piece of equipment to prepare the reagents, and reagent left in the reaction equipment for unspecified periods of time can cause corrosion trouble. Moreover, during and after treatment with the reagent, it is necessary to conduct and administer complicated and difficult procedures to recycle the reagent during and after treatment.
Moreover because the catalyst layer prepared by the use of reagents exhibits poor adhesion, and because it cannot endure long continuous use, this method exhibits the defect of almost all of the catalyst separating and falling away. Without even taking into account the loss of catalyst activity caused by the peeling off of the oxide layer, this results in the additional bad effect of contamination of the system by the metal oxides that have peeled off. The inventors of the present invention achieved the present invention as a result of intensive and purposeful research to discover a method for solving these problems.
The object of the present invention is to offer a method for producing catalyst for the synthesis of hydrocyanic acid by thermal decomposition of formamide which exhibits both high activity and stability over a long period of time.